1. Field of the Invention
The present invention relates generally to the field of levels which indicate the orientation of a surface relative to horizontal or vertical. More specifically the present invention relates to a level apparatus for indicating the tilt of an object surface toward or away from a user, or in other words along the user line of sight rather than across the user line of sight, such as for continuously indicating to a driver seated in a load-carrying fork lift truck the forward or rearward tilt of the truck to prevent hazardous forward or rearward instability, and for indicating to a construction worker whether an upright building element is truly vertical or is tilted toward or away from the worker. The level apparatus includes a fluid vessel containing an-indicator fluid in the form of a liquid which preferably is pigmented for easy visibility, the fluid vessel having a vessel abutment region with a rearward abutment wall for placing flat against a surface to be evaluated for tilt and with a forward display wall including a fluid display window extending perpendicular to the user line of sight with a fluid level indicating mark, the fluid surface being visible in the fluid display window when the abutment wall is upright and the apparatus is thus oriented for use, and includes a vessel reservoir region extending either rearwardly or forwardly from the vessel abutment region along the user line of sight, the vessel abutment region and vessel reservoir region being in mutual fluid communication so that fluid in the vessel reservoir region either flows into or out of the vessel abutment region depending on the tilt of the level along the user line of sight. The vessel reservoir region contains a sufficient quantity of fluid that forward or rearward tilting of the rearward abutment wall a number of degrees considered significant for the intended use creates a readily apparent change in the position of the fluid surface in the fluid display window relative to the fluid level indicating mark to make the tilt of the apparatus and object surface noticeable to the user. Another embodiment is provided in which the reservoir region is either omitted or combined into the abutment region so that the abutment region and reservoir region together define a single fluid chamber, which will be referred to as a display chamber. Tubular embodiments are also provided.
2. Description of the Prior Art
There have long been levels for determining whether an upright surface of an object tilts to the left or to the right across the user line of sight. A problem with these prior levels has been that they do not indicate the tilt of an upright surface toward or away from the user, along the user line of sight. The user is forced to circle around an object, such as a post or column, to take a series of level readings, or two users must take simultaneous level readings, along perpendicular directions. What is needed is a level apparatus which indicates tilt toward or away from a user, and which can be structurally combined with or used in combination with a conventional level, to indicate the tilt of an upright member along and across the line of sight at the same time.
It is thus an object of the present invention to provide a level apparatus which indicates to a user the orientation of an upright object relative to vertical along the line of sight of the user.
It is another object of the present invention to provide such a level apparatus which can be structurally combined with or used in combination with a conventional level to simultaneously indicate the tilt of an upright object both along and across the user line of sight.
It is still another object of the present invention to provide such a level apparatus which is operable in a fully inverted position to be reversible and fit around a left hand corner or around a right hand corner of an upright object and give the user the level reading.
It is finally an object of the present invention to provide such a level apparatus which is simple in design, compact, light in weight, sturdy and inexpensive to manufacture.